body{
  margin: 0px;
}
/* HTML: <div class="loader"></div> */
.loader {
  width: 120px;
  height: 20px;
  border-radius: 20px;
  background:
   radial-gradient(farthest-side,orange 94%,#0000) left/20px 20px no-repeat
   lightblue;
  animation: l2 1s infinite linear;
}
@keyframes l2 {
    50% {background-position:right }
}